The symbol in the centre of the "Hi-no-maru" (the Japanese national flag) is
the state "Mon" or emblem. It has been the state symbol of Japan for centuries.
The flag became the National Flag following the Meiji Restoration in 1868. It
never had rays.Graham Bartram, 09 November 1998

In 1999, Japan adopted new
legislation on the national flag. The legislation set an official national flag
with 2:3 proportion, and the sun disc at 3/5 of hoist length in the center with BENI-IRO
on white field.
A long time dispute was concluded on which flag should be official/legal national
flag whether decree no 651 of Oct 3, 1870 (2:3, 3/5, in the center) originally
legislated for the Japanese Naval flag or decree no 57 of Jan 27
1870 (7:10, 3/5, 1/100 towards hoist) originally legislated for the Japanese
Merchant flag.Nozomi Kariyasu, 5 August 1999, 22 January 2000

While Album des pavillons[pay00] gives
the Pantone color as red 186C, I have a fabric sample on file which suggests the
use of Pantone 193C.Christopher Southworth, 22 December 2005

Comparisons of old and new flag decrees
(Click on image to enlarge)

Decree No 127 (1999)

Decree No 57 (1870)

image
by Antonio Martins

image by Antonio Martins

Overall proportion

2:3

7:10

Placement of sun disc

centered

1/100th towards the hoist

Size of the sun disc

3/5 of hoist length

3/5 of hoist length

Historical Information

From: Japan: an illustrated encyclopedia Vol. 2 (M-Z):

national flag

(kokki). The national flag of Japan has a crimson disc, symbolizing the
sun, in the center of a white field. It is popularly known as the Hinomaru
(literally, "sun disc"). It is said that at the time of the Mongol Invasions
of Japan (1274 and 1281) the priest Nichiren presented a sun flag to the
shogun. The Tokugawa shogunate (1603-1867) adopted the flag for its ships
in the early 1600s. In the mid-19th century the shogunate decreed that all
Japanese ships fly flags with the sun on a white field. In 1870 the Meiji
government officially designated it for use on Japanese merchant and naval
ships. It has never been officially designated as the national flag; however,
it has become so by customary use. The "rising-sun" flag with 16 rays used
by the former Japanese navy and by the present Maritime Self Defense Forces
is a military service flag and should not be confused with the national
flag.

Beside a drawing of the flag is the following text:

The design and proportions of Japan's national flag were fixed in 1870
by the Meiji government. The vertical to horizontal ratio was set at 2:3,
the disc was to be placed at the exact center, and the diameter of the disc
was to equal three-fifths of the vertical measurement of the flag.

Marcus Schmöger, 27 August 2001

The name of Nichiren means the sun and lotus in English (Nichi = Nihon
= the sun; Ren = lotus ) and the lotus is a typical symbol of Buddhism. That
is why he gave the sun (and lotus) to the Shogun who at that time was politically
opposed to the Emperor (who was a God in Shintoism). Nichiren is said the
greatest Buddhist in Japan because a majority of Japanese are not Shintoist
but Buddhist. The Nichiren was formed his organization which is now called
Soka-Gakkai whose political part is Komei-tou which is composed of the present
Japanese cabinet.
I think he believed his flag could help the Shogun, who had military power,
to save Japan and the people from Mongol Invasion. He could not find any reason
for him to give his flag to the Emperor who is believed the God and son of
the Sun but who had no ability to defeat Mongolian.Nozomi Kariyasu, 29 August 2001

Nichiren's purpose was to motivate the political powers to abandon the
more popular Buddhist sects and to accept the Lotus Sutra as the one sure
way to save Japan. His was a religious and philosophical movement, not a political
one. At the same time he issued to the government a treatise entitled "Rissho
Ankoku Ron" which predicted great disaster for Japan should they not retreat
from the heretical (popular) Buddhist sects and accept his teachings.

On June 13, 1870, the Army "National Flag" was gazetted as a 16-ray Rising
Sun flag, 4 feet 4 inches by 5 feet, with the centrally-located sun disc
one-third the width of the flag. There was no fringe.

On October 27, 1870, The Navy "National Flag" was gazetted as the
Hinomaru, 7 feet 8 inches by 11 feet 7 inches, with the
centrally-located sun disc three-fifths the width of the flag. The
Jack was the same, but in 6 feet by 8 feet. Also gazetted were the
flag of the Emperor and the flag of the Imperial Family, shown as the Emperor's Flag, 1870-1879 and
Royal Family, 1976
(Family). Dimensions same as the "National Flag". These flags lasted
until October 8, 1889, when the current set of flags were adopted.

On July 30, 1912, to mark the passing of Emperor Meiji, the Hinomaru
was required to have a strip of black cloth flown above it, as well
as a black cloth to cover the flagpole's ball finial.

On March 25, 1931 the Imperial Diet attempted to legislate the
Hinomaru as the official National Flag and also its official
specifications; it passed the House of Commons, but did not go through
the House of Peers.

The protocol manual for the
London 2012 Olympics (Flags and Anthems Manual
London 2012 [loc12]) provides recommendations
for national flag designs. Each
NOC was sent an image of the flag,
including the PMS shades, for their approval by LOCOG. Once this was obtained, LOCOG produced
a 60 x 90 cm version of the flag for further approval. So, while these specs may
not be the official, government, version of each flag, they are certainly what
the NOC believed the flag to be.
For Japan: PMS 032 red.Ian Sumner, 10 October 2012

The Prime Minister's Proclamation No. 57 issued on January 27 in the
3rd Year of Neiji (1870):

Regulations of Merchant Ship (abridged)

1. The national flag:

This shall not be removed and even a ferryboat shall keep it hoisted.
Hoist it at 8 a.m. every morning and haul it down at sunset every evening.
In case of non-hoisting of the national flag it is customary of the
international law that no plea is justified it treated as pirates.

2. The dimensions of the national flag:

The ratio of the hoist and fly 7:10.
The diameter of the disc: three fifths of the hoist length of the
flag locating in the center.

Recently, I discovered a Japanese flag imposed with writing on it on
Yahoo Auctions. The auction
mentions the text imprinted on the flag is the lyrics of Kimi ga Yo, the Japanese
national anthem. I have seen this as patches and stickers, but this is
the first time I have actually seen it on cloth.Zachary Harden, 22 February 2008

A red disk bordered with white.
Just to mention, Military Aircraft
Insignia of the World explains that such a roundel was used
since the establishment of Japanese military aviation. It mentions
that sometimes the disk was also bordered yellow, and that on the
Home Defence aircrafts in 1944-45 the red disk was on white square
field. After the surrender in 1945, the Allies prescribed that all
Japanese aircrafts have their roundels painted white with green
cross throughout.Željko Heimer, 4 March 2002

The Japanese Air Force was formed in 1911 and a year later a
naval air arm was formed. After a period of no military aviation
in Japan, the Japan Air Self-Defense Force (Nihon Koku-Jieitai)
was formed on 1 July 1954 together with Japan Maritime Self-Defense
Force (Kaijyo Jieitai) and Japan Ground Self-Defense Force (Rikujo
Jieitai) with their air arms.Dov Gutterman, 18 June 2004

Reported Roundel (1915)

image by Marc Pasquin, 4 May 2006

Flipping through a book on the history of aviation, I came
upon the reproduction of a French poster from 1915 that showed
some planes of the world. Those that are visible (its only part
of the poster) carry what you would expect in terms of markings
but Japan was unusual:
Japan: a red 5-pointed star on a white circle. The star was
part of the uniform of the Japanese so this might explain its
use. the army probably switched to the more familiar one after
the Russian revolution to avoid confusion.Marc Pasquin, 4 May 2006